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Old 2005-12-31, 15:44   #1
nibble4bits
 
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Nov 2005

2·7·13 Posts
Default Some Psuedo-random stuff

Let's say that you have 2 possible values for an 1-bit PRNG.
The possible sequences: 0,1 and 1,0
What about 2-bits? 16 from 00,01,10,11 to 11,10,01,00
What if the psuedo-random number generator ran for 256 unique 8-bit charactors in a row, and then created a new group of 256 bytes every time it used them up?
How likely is this the next sequence to be accidentally the same? Would it be possible to break a 256-byte substitution box with little work with a known plaintext? Known language/format? Unknown but redundant file?
Why is this 256-byte key almost useless for text files even if totally random?

What I'm getting at is that all generators cycle but how bad is it and how easy is it to guess your current position (or even the key!) when there's single/multiple cycles.
Would it make a difference if you combined the first cycle with a second one (using the 2nd one to determine the rules for the first one in the current cycle)?

What if you just add values from the two cycles and they have 1 as the lowest common denominator?
Does the length of the total cycle double, add together, multiply, or what?

I'm sure this'll get the old nogging going.

Last fiddled with by nibble4bits on 2005-12-31 at 15:46
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